NEW YORK — Major League Soccer's referees and other on-field officials were locked out Friday, a day before the season openers.

The Professional Referee Organization, which manages game officials for the U.S. Soccer Federation and MLS, notified the Professional Soccer Referee Association of the lockout and said replacement officials will be used.

PRO said the union, which was formed last year, rejected a no strike-no lockout agreement that management had proposed. The sides have bargained since July without reaching a deal on a labor contract.